Pet Health Guide - Kidneys

The kidneys function as the filtration system for the entire body removing toxins, maintaining fluid balance and regulating electrolyte levels.

Kidney disease is not the same as kidney failure. Depending on the quantity of injury to the kidneys and duration, kidney disease may or may not lead to kidney failure. Kidney failure implies that two thirds to three fourths or more of the functional capacity of the kidneys has been impaired.

The term kidney failure is analogous to heart failure or liver failure in that a level of organ dysfunction is described rather than a specific disease entity.

Our goal, on this vary diverse topic, is to address the guidelines currently accepted in veterinary medicine on properly feeding dogs and cats afflicted with kidney dysfunction, whether or not kidney disease or kidney failure has been diagnosed.

Kidney dysfunction can affect dogs or cats at any age, but is predominantly seen in middle aged to older animals.

Clinical Signs

• Gastroenteritis Polyuria/Polydipsia (PU/PD)
• Hypertension
• Vomiting
• Protein in the urine
• Weight loss/dehydration
• Potassium loss
• Hypertension
• Behavioral changes (neuropathy)

Some animals with kidney disease typically “grown” when getting up and laying down somewhat similar to animals with arthritis. Often animals with kidney problems develop sensitivity to noise and display excessive fear with a desire to hide. Traditional Chinese Medicine practitioners commonly diagnose dogs with kidney dysfunction as displaying excessive itching, hot spots/red paws or dry skin in absence of other causes.

Kidney Disease & Diet Recommendations (Dogs)

Kidney insufficiency is a clinical syndrome resulting from the loss of kidney function. These functions are the elimination of toxins, maintaining the equilibrium of body electrolytes, metabolic and endocrine functions. The dietary objectives for kidney are:

1. Meet the nutritional requirements of the animal.
2. Minimize or remove clinical signs.
3. Minimize and help to restore the body’s fluid-electrolyte-vitamin/mineral and acid-base balance.
4. Slow the progression of the disease through specific diets, medications and supplements.

In order to achieve these goals, levels of energy, protein, minerals/electrolytes, fatty acids, fiber and vitamins are modified. Animals with kidney failure are often anorexic and have reduced appetites. Improving food intake should be attempted using whatever means necessary in order to get the animal to eat. Practical measures include feeding odorous foods, warming the food and positive reinforcement using petting and stroking. Appetite stimulants are always available and the implantation of a feeding tube may be necessary with severe kidney failure patients. Dogs should be evaluated by their veterinarians within 2 weeks of initiating any nutritional therapeutic program and then 3-4 times per year.

Feeding Plan Considerations

Energy (Kcal)
It is important to provide sufficient energy to prevent the loss of body proteins that lead to malnutrition and muscle loss. Loss of these body proteins results in a buildup of nitrogenous waste products in the body, referred to as a uremic state, with an elevation in blood urea nitrogen (BUN). Although the energy requirements for dogs with kidney dysfunction are not specific, they are believed to be similar to those of healthy animals. The energy feeding formula for dogs is 60 kcal x body weight/day. Maintenance energy levels can vary based on age, activity levels, etc. and therefore should be customized to meet the needs of the dog. Fats and carbohydrates provide the bulk of non-protein energy in the diet with fat providing twice the energy per gram than carbohydrates. With a need to restrict proteins, chronic kidney patients are better suited with a diet high in fat to meet energy needs.

Proteins
Clinical studies demonstrate that a reduction in dietary protein can reduce the level of nitrogenous waste products and phosphorus. Protein restriction is necessary only in dogs suffering with marked kidney failure. Reduced proteins and high non-protein (fat) calories are aimed at controlling the amount of nitrogenous wastes (BUN) and reducing or eliminating clinical signs even though kidney function may remain unchanged. Protein restriction also decreases the kidney’s workload and lessens the clinical signs of PU/PD. The recommended amount of protein intake per day for dogs is .90g/lb/day. For example: 50 lb dog x .90g=45 g protein/day.

Minerals & Electrolytes
Phosphate retention occurs early in kidney disease and is responsible for vitamin D deficiency and soft tissue calcification. Dietary restriction of phosphorus has been shown to slow the progression of kidney disease in dogs. Intestinal phosphate binders should be added to the diet if it cannot be reduced with 2-4 weeks using a low phosphate diet. Low phosphorus diets consist of 0.44% (dry matter) for dogs.

Hypertension has been reported in dogs with chronic kidney failure. The kidneys ability to excrete sodium (salt) is diminished which elevates systemic blood pressure. Therefore, dietary salt should be controlled to assist in reducing hypertension. Restricting dietary salt to a level of .1%-.3% of the diet will help control the secondary hypertension often seen in kidney compromised dogs. For example, a dog weighing 33 lbs. would receive approximately 200-600 mg of salt daily.

Mildly changing from the pet’s previous diet and salt concentration is recommended in dogs without hypertension and suffering the effects of kidney impairment. If sodium intake is rapidly reduced, dehydration and reduced kidney circulation may occur, with the possibility of irreversible kidney damage.

Potassium deficiency has been noted in dogs and cats with chronic renal failure. Therefore, supplementation with potassium gluconate should be considered. Similarly, the addition of alkalinizing agents (sodium bicarbonate, calcium carbonate or potassium citrate), to control the acid-base balance may be required.

Omega-3 Fatty Acids
Omega-3 fatty acid supplementation (menhaden fish) reduces kidney inflammation, lowers blood pressure and preserves kidney function. Omega-6 fatty acids (safflower oil) appears to increase kidney function and therefore be detrimental.

Water
Dogs with kidney impairment often run the risk of becoming dehydrated. Supplying plenty of fresh distilled water is necessary. Tap water and well water are not recommended because of the heavy mineral content which will increase the kidneys workload.

Canine Prescription Kidney Diets

** contains beet pulp/sugar

Dog Supplements

1. The phosphate and uremic binders in Epakitin and Azodyl safely and effectively decrease the kidney’s workload to help support normal kidney function by reducing B.U.N. and Creatinine levels.
2. Marine origin Omega-3 fatty acids, fed to dogs with kidney disease, provides high antioxidant properties.
3. A dietary fiber supplement such as Vetasyl for Dogs is an efficient way to achieve the necessary fiber levels that are beneficial to kidney patients.
4. Renal Essentials , used as a preventative supplement, has been formulated to help strengthen and maintain optimal kidney function in healthy dogs.

Kidney Disease & Diet Recommendations (Cats)

Inappetance is a common symptom in cats with kidney disease or failure. Improving food intake should be attempted using whatever means necessary in order to get the animal to eat. Practical measures include warming the food to body temperature, adding gravy and feeding small yet frequent meals. Cats should be evaluated by their veterinarians within 2 weeks of initiating any nutritional therapeutic program and then 3-4 times per year.

Feeding Plan Considerations

Energy (Kcal)
The feline energy feeding formula recommendation is 23-27 kcal/lb/day. For example, a cat weighing 12 lbs., would receive approximately 276-324 kcal /day. Non-protein energy from carbohydrates and fat can be increased to reduce the possibility of increased production of nitrogenous waste products. Fat is preferred for the kidney failure patient because it increases the energy density of the diet more than carbohydrates.

Proteins
The recommended amount of protein intake per day for cats is 1.69g/lb/day. For example: 10 lb cat x 1.69 g=16.9 g protein/day. Clinical studies have shown that modifying dietary protein can lower the nitrogenous waste products (BUN) and contribute to a healthier and longer life. When protein is restricted, dietary phosphorus is reduced which lessens the workload on the kidneys and slows the rate of kidney disease progression.

Minerals & Electrolytes
Low phosphorus diets consist of 0.24% (dry matter) for cats. Research has shown that cats fed a modified protein, low phosphate diet had increased survival times (2.4 times longer) than those fed a normal maintenance diet. Excess dietary sodium (salt) contributes to hypertension. The greater the amount of kidney damage or impairment, the less it can excrete sodium. Reduced or low sodium diets are recommended to prevent and control secondary hypertension.

Omega-3 Fatty Acids
Omega-3 fatty acid supplementation from menhaden fish reduces kidney inflammation, lowers blood pressure and preserves kidney function. Omega-6 fatty acids from safflower oil appears to increase kidney function and therefore become detrimental.

Fiber
Adding fiber (vetasyl) to the diet reduces the levels of phosphates, BUN and creatinine. This is a beneficial effect in addition to regulating gastrointestinal health.

Water
Cats with kidney impairment often run the risk of becoming dehydrated. Supplying plenty of fresh distilled water is necessary. Tap water and well water are not recommended because of the heavy mineral content which will increase the kidneys workload. More frequent litter box changes are often needed because cats with kidney disease urinate more frequently.

Feline Prescription Kidney Diets

Cat Supplements

1. The phosphate and uremic binders in Epakitin and Azodyl safely and effectively decrease the kidney’s workload to help support normal kidney function by reducing B.U.N. and Creatinine levels.
2. Marine origin Omega-3 fatty acids, fed to cats with kidney disease, provides high antioxidant properties.
3. A dietary fiber supplement such as Vetasyl for Cats is an efficient way to achieve the necessary fiber levels that are beneficial to kidney patients.
4. Renal Essentials, used as a preventative supplement, has been formulated to help strengthen and maintain optimal kidney function in healthy cats.